Propel and repel ball point pen mechanism

ABSTRACT

A retractable pen includes a barrel with relatively rotatable upper and lower sections. An axially movable plunger is located in the upper and lower sections and is provided with a top cam section having a top face with a peripheral helical cam surface terminating in an upper horizontal dwell section. The cam surface extends for less than 360* and terminates in stop shoulders at both ends. A vertical protruding rib is formed on the plunger and slideably engages a vertical slot in the barrel lower section while a projection on the upper section of the barrel engages the cam surface. A writing cartridge has its upper end engaging a well in the plunger and is upwardly spring urged.

United States Patent 1 July 25,1972

Liguori [54] PROPEL AND REPEL BALL POINT PEN MECHANISM [72] Inventor: Thomas A. Liguorl, Pelham Manor, NY.

[73] Assignee: Modern Mold & Tool Corp., Bronx, NY.

[22] Filed: Jan. 18, 1971 [21] Appl. No.: 106,996

[52] U.S. Cl ..40l/ll0 [51 Int. Cl ..B43k 24/06 [58] FieldoiSearch ..40l/l09-111, 116, 401/99, 62

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 509,871 3/1952 Belgium ...40l/1l0 1,004,813 12/1951 France ..40l/l10 Primary Examiner-Lawrence Charles Attorney-William R. Liberman [57] ABSTRACT A retractable pen includes a barrel with relatively rotatable upper and lower sections. An axially movable plunger is located in the upper and lower sections and is provided with a top cam section having a top face with a peripheral helical cam surface terminating in an upper horizontal dwell section. The cam surface extends for less than 360 and terminates in stop shoulders at both ends. A vertical protruding rib is formed on the plunger and slideably engages a vertical slot in the barrel lower section while a projection on the upper section of the barrel engages the cam surface. A writing cartridge has its upper end engaging a well in the plunger and is upwardly spring urged.

7 Claims, 8 Drawing Figures PROPIZL AND REPEL BALL POINT PEN MECHANISM BACKGROUND OF THE INVENTION The present invention relates generally to improvements in writing implements and it relates particularly to an improved retractable writing implement such as a retractable ball point pen.

The conventional ball point pen is generally of two types; one, wherein the ballpoint writing cartridge is axially fixed in the pen body member or is formed as a part thereof, and the second, wherein the writing element or cartridge is axially movable between an advanced position with the cartridge writing tip exposed and a retracted position with the writing cartridge retracted and fully housed in the pen body member or barrel. With the former type a cap is generally provided selectively to cover or uncover the end of the pen but this procedure is quite inconvenient. While the conventional retractable ball point pen overcomes the aforesaid drawback, the mechanisms heretofore employed for effecting the advance and retraction of the writing cartridge have usually been complicated, expensive and rather unreliable and inconvenient to operate, and they otherwise leave much to be desired.

SUMMARY OF THE INVENTION It is a principal object of the present invention to provide an improved writing implement.

Another object of the present invention is to provide an improved writing implement provided with a cam-controlled selectively advanced and retracted writing element.

Still another object of the present invention is to provide an improved retractable ball point pen.

A further object of the present invention is to provide a writing implement of the above nature characterized by its reliability, simplicity, low cost, ease and convenience of operation and great flexibility and adaptability.

The above and other objects of the present invention will become apparent from a reading of the following description taken in conjunction with the accompanying drawing which illustrates a preferred embodiment thereof.

In a sense, the present invention contemplates the provision of a retractable writing implement comprising a tubular barrel including relatively rotatable coaxial upper and lower sections, the sections being restricted against relative axial movement, said lower section having an axially apertured bottom tip, a plunger member having a lower part slidably engaging the upper part of said barrel lower section and axially movable therein, first means for restricting relative rotation between said plunger and said barrel lower section, a cam member positioned atop said plunger member and having a top face with a cam surface defining, longitudinally inclined peripheral border, a cam follower positioned on said upper barrel section and engaging said cam surface, an elongated writing element housed in said barrel and movable between an advanced position projecting through said barrel bottom aperture and a retracted position and engaging said plunger to be movable therewith, and a spring member urging said writing element toward its retracted position.

In its preferred form the upper portion of the barrel lower section telescopes the lower portion of the barrel upper section and they are interlocked against relative axial movement by a mating peripheral groove and rib formed on their respective confronting faces. The plunger is cylindrical and has vertical ribs in its outer face which slidably engage vertical slots formed in the barrel lower section upper part, an axial well being formed in the bottom of the plunger. The cam member is cylindrical and integrally formed with the top of the plunger and has an inclined top face provided with a horizontal upper section, one-half the peripheral border of the top face defining the cam surface, the other half being provided with an upwardly directed lip whose ends define stops. The follower includes an inwardly directed vertical rib formed on the barrel upper member inner face, the bottom of the rib engaging the cam surface. The writing element is a ball point cartridge having a radially projecting ear and having its upper end telescoping the plunger well and a helical compression spring encircles the lower section of the cartridge and is entrapped between the cartridge ear and the bottom part of the barrel.

The improved retractable pen is of extremely simple construction, the only member, in addition to the cartridge, spring and barrel sections, being the unitary plunger cam member. The pen is inexpensive and easy to make and assemble, and is highly reliable and simple and convenient to operate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of a retractable ball point pen embodying the present invention, the writing element being illustrated in a retracted position;

FIG. 2 is an enlarged fragmentary longitudinal sectional view taken along line 2-2 in FIG. 1;

FIG. 2A is a view similar to FIG. 2 with the plunger element shown in advanced position;

FIG. 3 is a longitudinal sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a transverse sectional view taken along line 44 in FIG. 2;

FIG. 5 is a transverse sectional view taken along line 55 in FIG. 2;

FIG. 6 is a front perspective view of the plunger cam member; and

FIG. 7 is a view of the resolved surface of the cam member.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing which illustrates a preferred embodiment of the present invention, reference numeral 10 generally designates the improved writing implement in the form of a retractable ball point pen which comprises a barrel member 11 including tubular upper and lower sections 12 and 13 respectively. Barrel sections 12 and 13 may be formed of any suitable material, for example a synthetic organic polymeric resin such as polystyrene, polyvinylchloride or the like and may be fabricated by any suitable method, such as by injection molding or otherwise.

Barrel lower section 13 is tubular with its upper part of cylindrical configuration and tapering inwardly downwardly to an open ended bottom tip 14. The upper portion 16 of barrel lower section 13 is of reduced outside diameter and is delineated from the main body thereof by an upwardly facing annular shoulder 17. An annular groove 18 of rectangular transverse cross section is formed in the outer face of barrel portion 16 a short distance above shoulder 17 and a pair of diametrically opposed vertical slots 19 are formed in barrel portion 16 and extend from the upper edge thereof to points shortly above annular groove 18.

Barrel upper section 12 is of the form of a cylindrical tubular cap open at its bottom and closed at its top by a curved wall. The outside diameter of barrel section 12 is about equal to that of the main portion of barrel section 13 and its inside diameter is approximately equal to or slightly greater than the outside diameter of barrel portion 16. Barrel portion 16 telescopes the lower part of barrel section 12 with the lower edge of barrel section 12 rotatably engaging shoulder 17, and an annular rib 20, substantially mating groove 18, rotatably engages groove 18 to prevent axial movement between barrel sections 12 and 13 while permitting their relative rotation. Integrally formed with barrel section 12 on the upper inner face thereof is a cam follower vertical rib 21 rounded at its bottom end 22 and extending to the upper curved part of barrel section 12.

An axially movable plunger member 23 is disposed in barrel 1] and includes a relatively long cylindrical lower plunger section 24 reciprocatingly slidable telescoping barrel section 13 and an integrally formed relatively short cylindrical upper cam section 26 of greater diameter than plunger section 24 and slidably registering with the inside face of barrel section 12.

An axial bore or well 27 is formed in the underface of plunger section 24 and extend for substantially the full length thereof. In order to prevent relative rotation between plunger member 23 and barrel section 13 while permitting relative axial movement thereof, a pair of diametrically opposite vertical ribs 28 are formed on the peripheral face of plunger section 24 and extend from the top thereof to points intermediate its ends. Ribs 28 slidably engage slots 19 in barrel portion 16.

Top face 29 of cam section 26 is inclined, the upper portion 30 thereof however, being horizontal. A vertical peripheral wall 32 projects above the edge of inclined face 29 and extends from the bottom point of inclined face 29 for less than 180 to the proximate end of the peripheral edge of horizontal portion 30. The opposite end edges 33 of wall 32 are vertical and define stops, the border 34 of face 29 uncovered by wall 32 defining a cam surface including a helical inclined cam section 36 and an upper horizontal cam dwell section 37, the cam surface terminating at stops 33. The lower end of cam follower 21 normally slideably engages the cam surface 34.

A ball point cartridge or other writing element 38 is axially positioned in barrel 1 l with its upper end nested in well 27 and abutting the upper end face thereof and its writing or tipend 39 registering with the opening in barrel tip 14. Writing element 38 is resiliently urged to its retracted position to resiliently raise plunger member 23 by a helical compression spring 41 engaging the lower part of writing element 38 and entrapped between the lower inner face of barrel tip 14 and a pair of opposite lugs or ears 40 integrally formed on writing element 38.

Considering now the operation of the improved retractable ball point 10, in the retracted position of element 38, as shown in FIGS. 1, 2 and 3, writing element 38 and plunger member 23 are maintained in their retracted and raised position by the partially compressed extended helical spring 41. In the aforesaid retracted position cam follower 22 engages the lower end of cam surface 36 and abuts a corresponding stop 33. To propel writing element 38 to its advanced position with writing tip 39 projecting from barrel 11, barrel upper section 12 is rotated clockwise relative to barrel lower section 13 so that cam follower 21 moves clockwise along cam surface 34 thereby axially advancing plunger member 23 and writing element 38 to their lowered positions against the pressure of spring 41. When plunger member 23 and writing element 38 are fully advanced cam follower 21 engages the horizontal dwell surface 37 and abuts corresponding stop 33 so that the plunger member 23 and writing element 38 are releasably locked in their advanced positions against the influence of fully compressed helical spring 41. To retract the writing element the barrel section 12 is rotated about 180 counterclockwise relative to barrel section 13 to relieve the pressure of follower 21 on cam surface 34 and permit spring 41 to urge writing element 38 and plunger member 23 to their retracted positions.

The pen may be easily and rapidly assembled by positioning writing element 38 with engaged spring 41 and plunger member 23 engaging the top of writing element 38 as illustrated, in the lower barrel section 13, with ribs 28 engaging slots 19. Upper barrel section 12 is coaxially oriented with I them apart with sufficient force to permit access to and replacement of cartridge 38. However, the latter operation is not necessary since the pen 10 may be a throw away item because of its very low cost.

While there has been described and illustrated a preferred embodiment of the present invention, it is apparent that numerous alterations, omissions and additions may be made without departing from the spirit thereof,

I claim:

1. A protractable and retractable writing implement comprising a tubular barrel including relatively rotatable coaxial upper and lower sections restricted against relative axial movement, said lower section having an axially apertured bottom tip and a vertically extending recess formed in the upper part thereof, an axially movable plunger member having a lower part slideably engaging the upper part of said barrel lower section and axially movable therein and a cylindrical upper part slidably engaging the inside face of said barrel upper section, a protuberance located on the outer face of said plunger and slidably engaging said vertically extending recess, a cam located at the upper part of said plunger member and including an inclined, peripheral, upwardly facing cam surface, a cam follower integrally formed with and directed inwardly from the inside face of said upper barrel section and engaging said cam surface, an elongated writing element housed in said barrel and movable between a protracted position projecting through said barrel bottom aperture and a retracted position and engaging said plunger to be movable therewith, and a spring member urging said writing element toward its retracted position.

2. The writing implement of claim 1 wherein said cam surface is an ascending and descending part spiral.

3. The implement of claim 1 wherein said cam surface includes a horizontal dwell section at the upper end thereof.

4. The implement of claim 3 wherein said cam surface extends for less than the full periphery of said cam member and includes a peripherally extending lip projecting upwardly from said cam top face and joining the opposite ends of said cam surface.

5. The implement of claim 1 wherein said plunger member has an axial well formed in the bottom thereof, the upper end of said writing element telescoping said well.

6. The implement of claim 1 wherein the proximate end portions of said upper and lower barrel sections are in telescoping relationship, the confronting faces of said telescoping portions having rotatably mating ridge and groove formed therein to permit the relative rotation of said barrel sections while restricting their relative axial movement.

7. The implement of claim 1 wherein the inside bore of said barrel upper section is of greater diameter than that of said barrel lower section and said cam member is of greater diameter than said plunger member. 

1. A protractable and retractable writing implement comprising a tubular barrel including relatively rotatable coaxial upper and lower sections restricted against relative axial movement, said lower section having an axially apertured bottom tip and a vertically extending recess formed in the upper part thereof, an axially movable plunger member having a lower part slideably engaging the upper part of said barrel lower section and axially movable therein and a cylindrical upper part slidably engaging the inside face of said barrel upper section, a protuberance located on the outer face of said plunger and slidably engaging said vertically extending recess, a cam located at the upper part of said plunger member and including an inclined, peripheral, upwardly facing cam surface, a cam follower integrally formed with and directed inwardly from the inside face of said upper barrel section and engaging said cam surface, an elongated writing element housed in said barrel and movable between a protracted position projecting through said barrel bottom aperture and a retracted position and engaging said plunger to be movable therewith, and a spring member urging said writing element toward its retracted position.
 2. The writing implement of claim 1 wherein said cam surface is an ascending and descending part spiral.
 3. The implement of claim 1 wherein said cam surface includes a horizontal dwell section at the upper end thereof.
 4. The implement of claim 3 wherein said cam surface extends for less than the full periphery of said cam member and includes a peripherally extending lip projecting upwardly from said cam top face and joining the opposite ends of said cam surface.
 5. The implement of claim 1 wherein said plunger member has an axial well formed in the bottom thereof, the upper end of said writing element telescoping said well.
 6. The implement of claim 1 wherein the proximate end portions of said upper and lower barrel sections are in telescoping relationship, the confronting faces of said telescoping portions having rotatably mating ridge and groove formed therein to permit the relative rotation of said barrel sections while restricting their relative axial movement.
 7. The implement of claim 1 wherein the inside bore of said barrel upper section is of greater diameter than that of said barrel lower section and said cam member is of greater diameter than said plunger member. 